AusBonsai

I have only had one Wisteria stock plant and it has a very compact root ball. Last year it struggled with little water, but it flowered much better this year with ample water.

Try this:
http://crataegus.com/2012/01/06/why-won ... ria-bloom/

I'd fill the bottom quarter of the bucket and keep it at that level. When you fertilise, I'd do that out of the bucket, I'm just not sure about leaving it in fert all growing season